Die-cast cylinder lock



Aug. 19, 1937. c. L. COUGHLIN DIE CAST CYLINDER LOCK Filed NOV. 18, 1955 Patented Aug. 10, 1937 UNITED STATES PATENT QFFIQE DIE-CAST CYLINDER LO CK Application November 18, 1935, Serial No. 50,329

1 Claim.

This invention relates to the treatment of die castings and particularly to the treatment of the die-cast parts of cylinder locks.

As is well known, the casings and plugs or cylinders of cylinder locks are now generally diecast, and inasmuch as die-cast metal is notoriously subject to the destructive effects of corrosion, difliculty has been experienced in preventing mechanical freezing of the cylinders or plugs in their casings, especially when the locks are infrequently operated.

Besides the necessity for maintaining the plugs or cylinders free in their casings, it is also essential that the tumblers be kept free at all times.

This latter requirement has proved exceptionally troublesome as the tumblers of cylinder locks are comparatively small and their passages or chambers in which they operate are consequently restricted. It is thus impossible to maintain sufficient artificiallubrication in the tumbler chambers to preclude mechanical freezing of the tumblers for long, and even the selection of a lubricant for this purpose presents difiiculties for the reason that the locks are often subjected to severely cold temperatures which cause whatever lubricant is used to congeal to the extent of entirely preventing free and proper functioning of the lock parts.

There are thus two major problems to be con- 0 sidered in the use of die-cast metal for cylinder locks and the like, namely, the inevitable and rapid corrosion of the die-cast metal, and the difficulty of providing proper lubrication.

The present invention is directed to these particular problems and has as its object to provide a simple treatment for die castings and particularly the die-cast parts of cylinder locks to effectually retard the corrosion thereof and afford inherent lubrication for the component parts of a cylinder lock.

More specifically it is an object of this invention to provide a treatment for die castings by which their internal structure becomes saturated at least to a substantial depth with oil which not only has the ability to effectually retard corrosion, but also provides lubrication when the die castings are used as part of a mechanism such as a cylinder lock wherein the die castings have sliding surface to surface engagement with other parts.

With the above and other objects in View which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claim, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claim.

The accompanying drawing illustrates one 5 complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a side View of a die-cast lock cylin- 1O der or plug with a part broken away and in section;

Figure 2 is a side View of a die-cast lock casing also with a part broken away and in section;

Figure 3 is a diagrammatic view illustrating 15 the manner of treatment; and

Figure 4 is an enlarged cross section view through a portion of a die casting to illustrate how the oil penetrates into the pores thereof.

Referring now more particularly to the ac- 2O companying drawing in which like numerals indicate like parts throughout the several views, the numeral 5 designates the lock cylinder or plug of a conventional cylinder lock which, as is customary, is rotatably received in the bore 6 of 25 a casing 1. Both the plug 5 and the casing l are die castings.

The plug 5 is provided with a longitudinal keyway 8 communicating with a plurality of tumbler guideways 9 in which tumblers (not shown) 30 are adapted to be slidably disposed. The tumblers are usually spring held in operative locked positions and retractible to inoperative unlocked positions by the insertion of a proper key into the keyway 8.

In some cylinder locks the tumblers are projectible from the peripheral wall ill of the plug into cooperative engagement with tumbler grooves (not shown) in the casing I. In the look here illustrated as in Patent No. 1,965,336 issued to 40 John W. FitzGerald July 3, 1934, the tumblers do not project beyond the surface of the cylinder or plug during operation but coast with a locking bar (not shown) projectible from a recess H in the side of the cylinder by the tumblers. 45

In all instances, however, the tumblers and their associated mechanism is comparatively small and the passages in which they operate are correspondingly restricted. Consequently, it is diflicult to maintain proper lubrication through- 50 out the life of the lock especially in view of the injurious effects of corrosion to which the diecast plug 5 and easing l are subjected.

The corrosion of the cylinder or plug and the casing is effectually retarded and undiminished 55 lubrication for the mechanism of the lock is provided by. treating these die-cast parts of the lock in a manner to be now described.

It is a known fact that die-cast metal has a 5 degree of bibulosity and a marked aflinity for oil under certain conditions. These characteristics of die-cast metal are utilized in the present treatment and make possible the saturation of the die castings at least to a substantial depth with a fluid lubricant. To this end, the die castings are subjected to a bath of oil of sufliciently light viscosity to penetrate into the microscopic pores of the die-cast metal.

One method of subjecting the castings to this oil treatment, as illustrated in Figure 3, consists in immersing the same in a bath of oil of the desired light viscosity which has been heated to a temperature of approximately 150 F.

A structure particularly suitable for this pure pose consists of a tank 14 containing the heated oil and a rack l5 extending across the open top thereof from which supportnig hooks l6 are suspended. The castings to be treated are mounted on the hooks, as shown. As hereinbefore indicated, oil of a sufiiciently light viscosity, preferably between a No. 10 and a No. 20 S. A. E. is used, and while not necessary, it has been found desirable to incorporate in this oil bath a small percentage of graphite. The 0 amount of graphite used may be between th of 1% to 2% by weight, and it is preferably applied in an oil floated form. The addition of the graphite to the oil affords a more permanent protection against corrosion and insures better lubrication.

The period of time for which the castings are submersed in the oil bath depends of course upon the cross sectional size of the castings, it being preferable to continue the oil treatment for a period long enough to insure substantial saturation of the internal structure of the casting as illustrated in Figure 4.

Die castings treated in accordance with this invention are effectually protected against the destructive effects of corrosion for an exceptionally long period of time and by reason of the fact that the oil which has penetrated into the body of the casting exudes therefrom during the life of the mechanism in which it is used, the outer surfaces thereof are constantly provided with a film of lubricant to preclude mechanical freezing of relatively movably associated parts.

From the foregoing description taken in connection with the accompanying drawing, it will be readily apparent to those skilled in the art, that this invention provides a novel treatment for die castings generally and particularly for the die-cast parts of cylinder locks by which corosion is retarded and inherent lubrication is afforded.

What I claim as my invention is:

In a cylinder look, a casing having a bore, a plug mounted in said bore with its outer cylindrical surface in sliding engagement with the Wall of the bore and having tumbler and key receiving passages with the walls thereof adapted to slidably mount the tumblers of the lock and guide the key for coaction therewith, said casing and plug being separate die-cast units and the internal structure of said units being microscopically porous and having their pores filled at least to a substantial depth with a fluid lubricant having the ability to penetrate into the internal structure of said units whereby said units are protected against corosion and the slidably engaged surfaces of the units and the walls of the tumbler and key receiving passages of the plug are inherently lubricated.

CHARLES L. COUGHLIN. 

